Gürbüz Gökçen profile image
Gürbüz Gökçen Prof. Dr. MARMARA ÜNİVERSİTESİ
Publication 24 Review 50 CrossRef Cited 112 TR Dizin Cited 58
24 Publication
50 Review
112 CrossRef Cited
58 TR Dizin Cited
0000-0001-9854-8522

Research Fields

Financial Accounting International Accounting Management Accounting

Institution

MARMARA ÜNİVERSİTESİ

Popular Publications

E-BOOK AND E-INVOICING PRACTICES FROM ACCOUNTING PRACTICES IN TURKEY
Authors: Gürbüz Gökçen , Mustafa Özdemir
Published: 2016 , Oneri
DOI: -
CITED 7 FAVORITE 1 TOTAL DOWNLOAD COUNT 11717

7

1

11717

Katılım Bankalarının Finans Sektörü İçindeki Yeri ve Katılım Bankalarına Yönelik Müşteri Algısı
Authors: İbrahim Gönen , Gürbüz Gökçen
Published: 2017 , Research of Financial Economic and Social Studies
DOI: -
CITED 0 FAVORITE 1 TOTAL DOWNLOAD COUNT 5021

0

1

5021

INVESTIGATION OF THE FULL COST AND THE NORMAL COST METHODS IN THE FRAMEWORK OF THE IFRS (TFRS) AND THE BOBİ FRS REGULATIONS
Authors: Gürbüz Gökçen , Erkan Öztürk
Published: 2017 , Research of Financial Economic and Social Studies
DOI: -
CITED 0 FAVORITE 1 TOTAL DOWNLOAD COUNT 13380

0

1

13380

ADAPTATION of FINANCIAL STATEMENTS BASED on GENERAL COMMUNIQUE ON ACCOUNTING SYSTEM APPLICATION (GCASA) to FINANCIAL REPORTING STANDARD for LARGE and MEDIUM SIZED ENTERPRISES (FRS for LMEs) and A RATIO ANALYSIS
Authors: Hakan Cavlak , Başak Ataman , Gürbüz Gökçen
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.424763
CITED 5 FAVORITE 1 TOTAL DOWNLOAD COUNT 10095

5

1

10095

COMPARISON OF BOBİ FRS AND TFRS IN TERMS OF THE EFFECTS OF FINANCIAL REPORTS
Authors: Erkan Öztürk , Gürbüz Gökçen , Ömer Faruk Güleç
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.425384
CITED 18 FAVORITE 1 TOTAL DOWNLOAD COUNT 11019

18

1

11019

Publications

PARTICIPATION BANKING IN TURKEY AND THE NEED FOR INFLATION ACCOUNTING IN PARTICIPATION BANKS: A CONCEPTUAL ANALYSIS WITHIN THE SCOPE OF TMS 29
Authors: Gürbüz Gökçen , Bünyamin Özdoğan
Published: 2026 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1941915
FAVORITE 0 TOTAL DOWNLOAD COUNT 235

0

235

THE EFFECT OF MANAGERIAL ACCOUNTING PRACTICES IN FINANCIAL CRISES ON PORTER'S GENERAL STRATEGIES
Authors: Gürbüz Gökçen , Selman Görgülü
Published: 2025 , International Journal of Management Economics and Business
DOI: 10.17130/ijmeb.1702770
FAVORITE 0 TOTAL DOWNLOAD COUNT 831

0

831

THE EFFECTS OF MANAGERIAL ACCOUNTING PRACTICES ON KEY COMPETITIVE STRATEGIES UNDER UNUSUAL FINANCIAL CONDITIONS
Authors: Selman Görgülü , Gürbüz Gökçen
Published: 2025 , Muhasebe ve Denetime Bakış
DOI: 10.55322/mdbakis.1708031
FAVORITE 0 TOTAL DOWNLOAD COUNT 440

0

440

FINANCIAL CRISES IN THE WORLD AND TURKEY EFFECTS OF FINANCIAL CRISES ON BUSINESSES
Authors: Selman Görgülü , Gürbüz Gökçen
Published: 2025 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1626319
FAVORITE 0 TOTAL DOWNLOAD COUNT 4561

0

4561

The effect of financial ratios of companies traded in the automotive sector on market value on Borsa Istanbul: an econometric analyis
Authors: Selin Korkmaz , Gürbüz Gökçen
Published: 2025 , Journal of Interdisciplinary Innovation Studies
DOI: 10.56723/dyad.1499063
FAVORITE 1 TOTAL DOWNLOAD COUNT 898

1

898

IFRS 18 PRESENTATION AND DISCLOSURE IN FINANCIAL STATEMENTS: A NEW APPROACH TO FINANCIAL PERFORMANCE MEASUREMENT
Authors: Erkan Öztürk , Ömer Faruk Güleç , Gürbüz Gökçen
Published: 2024 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1572623
FAVORITE 1 TOTAL DOWNLOAD COUNT 2635

1

2635

SPECIAL ISSUES WITHIN THE SCOPE OF FINANCIAL REPORTING IN HYPERINFLATIONARY ECONOMIES
Authors: Gürbüz Gökçen , Erkan Öztürk
Published: 2023 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1299626
FAVORITE 0 TOTAL DOWNLOAD COUNT 2793

0

2793

THE IMPACTS OF THE COVID-19 PANDEMIC ON SECTORAL PERFORMANCE: A REVIEW ON THE BIST SECTORS IN TURKEY
Authors: Başak Ataman , Gürbüz Gökçen , Kezban Şimşek
Published: 2022 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1105014
FAVORITE 0 TOTAL DOWNLOAD COUNT 1136

0

1136

FAİZSİZ FİNANS VE MUHASEBE STANDARTLARI (FFMS) KAPSAMINDA DÜZENLENEN FİNANSAL TABLOLARIN İNCELENMESİ VE TÜRKİYE FİNANSAL RAPORLAMA STANDARTLARI (TFRS) /TÜRKİYE MUHASEBE STANDARTLARI (TMS) İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen
Published: 2021 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.993335
FAVORITE 1 TOTAL DOWNLOAD COUNT 2594

1

2594

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI (FRSHP) ile TEKDÜZEN HESAP PLANI (TDHP) BİLANÇO HESAP GRUPLARININ KARŞILAŞTIRILMASI VE DEĞERLENDİRMESİ
Authors: Başak Ataman , Gürbüz Gökçen
Published: 2021 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.868910
FAVORITE 1 TOTAL DOWNLOAD COUNT 4267

1

4267

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI TASLAĞI’NDAKİ ÜRETİM MALİYETİ HESAPLARININ İNCELENMESİ VE TEKDÜZEN HESAP PLANI İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen , Başak Ataman
Published: 2020 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.833359
FAVORITE 1 TOTAL DOWNLOAD COUNT 3520

1

3520

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI TASLAĞI’NDAKİ HİZMET ÜRETİM MALİYETİ HESAPLARININ İNCELENMESİ VE TEKDÜZEN HESAP PLANI İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen , Başak Ataman
Published: 2020 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.739402
FAVORITE 0 TOTAL DOWNLOAD COUNT 4099

0

4099

CONTENT ANALYSIS IN BORSA ISTANBUL REGARDING FAIR VALUE HIERARCHY
Authors: Yasin Cebeci , Gürbüz Gökçen
Published: 2019 , Journal of Research in Business
DOI: -
FAVORITE 1 TOTAL DOWNLOAD COUNT 2116

1

2116

COMPARISON OF THE BASIC ISSUES BETWEEN KUMI FRS, BOBI FRS AND TAS/TFRS
Authors: Erkan Öztürk , Gürbüz Gökçen , Ömer Faruk Güleç
Published: 2019 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.616662
FAVORITE 1 TOTAL DOWNLOAD COUNT 6035

1

6035

İŞLETMELERDE HİLELERİN ÖNLENMESİNE YÖNELİK İÇ KONTROLLER VE BİST İMALAT SEKTÖRÜNDE BİR ARAŞTIRMA
Authors: Gürbüz Gökçen , Onur Tipi
Published: 2019 , Marmara University Journal of Economic and Administrative Sciences
DOI: 10.14780/muiibd.582316
FAVORITE 1 TOTAL DOWNLOAD COUNT 5764

1

5764

BİRLEŞİK İMALATTA ORTAK VE YAN MAMULLERİN MALİYETLERİNİN HESAPLANMASI VE ENTEGRE ET TESİSİNDE BİR UYGULAMA
Authors: İsmail Altuğ Baysak , Gürbüz Gökçen
Published: 2019 , Ida Academia Muhasebe ve Maliye Dergisi
DOI: -
FAVORITE 0 TOTAL DOWNLOAD COUNT 3093

0

3093

ADAPTATION of FINANCIAL STATEMENTS BASED on GENERAL COMMUNIQUE ON ACCOUNTING SYSTEM APPLICATION (GCASA) to FINANCIAL REPORTING STANDARD for LARGE and MEDIUM SIZED ENTERPRISES (FRS for LMEs) and A RATIO ANALYSIS
Authors: Hakan Cavlak , Başak Ataman , Gürbüz Gökçen
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.424763
FAVORITE 1 TOTAL DOWNLOAD COUNT 10095

1

10095

COMPARISON OF BOBİ FRS AND TFRS IN TERMS OF THE EFFECTS OF FINANCIAL REPORTS
Authors: Erkan Öztürk , Gürbüz Gökçen , Ömer Faruk Güleç
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.425384
FAVORITE 1 TOTAL DOWNLOAD COUNT 11019

1

11019

INVESTIGATION OF THE FULL COST AND THE NORMAL COST METHODS IN THE FRAMEWORK OF THE IFRS (TFRS) AND THE BOBİ FRS REGULATIONS
Authors: Gürbüz Gökçen , Erkan Öztürk
Published: 2017 , Research of Financial Economic and Social Studies
DOI: -
FAVORITE 1 TOTAL DOWNLOAD COUNT 13380

1

13380

Analysis Of The Relationship Between Corporate Governance Perception And Corporate Governance Rating
Authors: Başak Ataman , Gürbüz Gökçen , Hakan Cavlak , Yasin Cebeci
Published: 2017 , Journal of Finance Letters
DOI: 10.33203/mfy.307179
FAVORITE 0 TOTAL DOWNLOAD COUNT 5917

0

5917

Katılım Bankalarının Finans Sektörü İçindeki Yeri ve Katılım Bankalarına Yönelik Müşteri Algısı
Authors: İbrahim Gönen , Gürbüz Gökçen
Published: 2017 , Research of Financial Economic and Social Studies
DOI: -
FAVORITE 1 TOTAL DOWNLOAD COUNT 5021

1

5021

E-BOOK AND E-INVOICING PRACTICES FROM ACCOUNTING PRACTICES IN TURKEY
Authors: Gürbüz Gökçen , Mustafa Özdemir
Published: 2016 , Oneri
DOI: -
FAVORITE 1 TOTAL DOWNLOAD COUNT 11717

1

11717

A Research About Utilization Of Inventory Cost Formulas Under TMS 2 Inventory Standards In Food Sector
Authors: Gürbüz Gökçen , Yasin Cebeci
Published: 2016 , Journal of Finance Letters
DOI: 10.33203/mfy.312138
FAVORITE 0 TOTAL DOWNLOAD COUNT 9336

0

9336

A RESEARCH ON ACCOUNTING STANDARDS EDUCATION IN THE STATE UNIVERSITY GRADUATE PROGRAM IN TURKEY
Authors: Gürbüz Gökçen , Başak Ataman , Yasin Cebeci , Hakan Cavlak
Published: 2015 , Oneri
DOI: -
FAVORITE 0 TOTAL DOWNLOAD COUNT 2476

0

2476

Articles published in
Ida Academia Muhasebe ve Maliye Dergisi
Ida Academia Muhasebe ve Maliye Dergisi
International Journal of Management Economics and Business
International Journal of Management Economics and Business
Journal of Finance Letters
Journal of Finance Letters
Journal of Interdisciplinary Innovation Studies
Journal of Interdisciplinary Innovation Studies
Journal of Research in Business
Journal of Research in Business
Marmara University Journal of Economic and Administrative Sciences
Marmara University Journal of Economic and Administrative Sciences
Muhasebe ve Denetime Bakış
Muhasebe ve Denetime Bakış
Oneri
Oneri
Research of Financial Economic and Social Studies
Research of Financial Economic and Social Studies
Editorial Board Memberships
International Journal of Accounting and Finance Researches
International Journal of Accounting and Finance Researches

Reviews

Academic Review of Economics and Administrative Sciences
Academic Review of Economics and Administrative Sciences
Ahi Evran Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
Ahi Evran Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
Anadolu Üniversitesi İktisadi ve İdari Bilimler Fakültesi Dergisi
Anadolu Üniversitesi İktisadi ve İdari Bilimler Fakültesi Dergisi
Çukurova Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
Çukurova Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
EKOIST Journal of Econometrics and Statistics
EKOIST Journal of Econometrics and Statistics
Hatay Mustafa Kemal Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
Hatay Mustafa Kemal Üniversitesi Sosyal Bilimler Enstitüsü Dergisi
Ida Academia Muhasebe ve Maliye Dergisi
Ida Academia Muhasebe ve Maliye Dergisi
JOEEP: Journal of Emerging Economies and Policy
JOEEP: Journal of Emerging Economies and Policy
Journal of Accounting and Taxation Studies
Journal of Accounting and Taxation Studies
Journal of Economics Business and Political Researches
Journal of Economics Business and Political Researches
Journal of Finance Letters
Journal of Finance Letters
Journal of Management and Economics Research
Journal of Management and Economics Research
Journal of Social Sciences Institute of Mersin University
Journal of Social Sciences Institute of Mersin University
Kafkas University Journal of Economics and Administrative Sciences Faculty
Kafkas University Journal of Economics and Administrative Sciences Faculty
Muhasebe ve Denetime Bakış
Muhasebe ve Denetime Bakış
Research of Financial Economic and Social Studies
Research of Financial Economic and Social Studies
Süleyman Demirel University Visionary Journal
Süleyman Demirel University Visionary Journal
The Journal of Accounting and Finance
The Journal of Accounting and Finance
The Journal of Selcuk University Social Sciences Institute
The Journal of Selcuk University Social Sciences Institute
The World of Accounting Science
The World of Accounting Science
Trakya University Journal of Social Science
Trakya University Journal of Social Science
Uluslararası Bankacılık Ekonomi ve Yönetim Araştırmaları Dergisi
Uluslararası Bankacılık Ekonomi ve Yönetim Araştırmaları Dergisi

Publications

THE EFFECTS OF MANAGERIAL ACCOUNTING PRACTICES ON KEY COMPETITIVE STRATEGIES UNDER UNUSUAL FINANCIAL CONDITIONS
Authors: Selman Görgülü , Gürbüz Gökçen
Published: 2025 , Muhasebe ve Denetime Bakış
DOI: 10.55322/mdbakis.1708031
CITED 1 FAVORITE 0 TOTAL DOWNLOAD COUNT 440

1

0

440

FINANCIAL CRISES IN THE WORLD AND TURKEY EFFECTS OF FINANCIAL CRISES ON BUSINESSES
Authors: Selman Görgülü , Gürbüz Gökçen
Published: 2025 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1626319
CITED 2 FAVORITE 0 TOTAL DOWNLOAD COUNT 4561

2

0

4561

The effect of financial ratios of companies traded in the automotive sector on market value on Borsa Istanbul: an econometric analyis
Authors: Selin Korkmaz , Gürbüz Gökçen
Published: 2025 , Journal of Interdisciplinary Innovation Studies
DOI: 10.56723/dyad.1499063
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 898

1

1

898

IFRS 18 PRESENTATION AND DISCLOSURE IN FINANCIAL STATEMENTS: A NEW APPROACH TO FINANCIAL PERFORMANCE MEASUREMENT
Authors: Erkan Öztürk , Ömer Faruk Güleç , Gürbüz Gökçen
Published: 2024 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1572623
CITED 5 FAVORITE 1 TOTAL DOWNLOAD COUNT 2635

5

1

2635

SPECIAL ISSUES WITHIN THE SCOPE OF FINANCIAL REPORTING IN HYPERINFLATIONARY ECONOMIES
Authors: Gürbüz Gökçen , Erkan Öztürk
Published: 2023 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1299626
CITED 11 FAVORITE 0 TOTAL DOWNLOAD COUNT 2793

11

0

2793

THE IMPACTS OF THE COVID-19 PANDEMIC ON SECTORAL PERFORMANCE: A REVIEW ON THE BIST SECTORS IN TURKEY
Authors: Başak Ataman , Gürbüz Gökçen , Kezban Şimşek
Published: 2022 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.1105014
CITED 3 FAVORITE 0 TOTAL DOWNLOAD COUNT 1136

3

0

1136

FAİZSİZ FİNANS VE MUHASEBE STANDARTLARI (FFMS) KAPSAMINDA DÜZENLENEN FİNANSAL TABLOLARIN İNCELENMESİ VE TÜRKİYE FİNANSAL RAPORLAMA STANDARTLARI (TFRS) /TÜRKİYE MUHASEBE STANDARTLARI (TMS) İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen
Published: 2021 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.993335
CITED 1 FAVORITE 1 TOTAL DOWNLOAD COUNT 2594

1

1

2594

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI (FRSHP) ile TEKDÜZEN HESAP PLANI (TDHP) BİLANÇO HESAP GRUPLARININ KARŞILAŞTIRILMASI VE DEĞERLENDİRMESİ
Authors: Başak Ataman , Gürbüz Gökçen
Published: 2021 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.868910
CITED 7 FAVORITE 1 TOTAL DOWNLOAD COUNT 4267

7

1

4267

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI TASLAĞI’NDAKİ ÜRETİM MALİYETİ HESAPLARININ İNCELENMESİ VE TEKDÜZEN HESAP PLANI İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen , Başak Ataman
Published: 2020 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.833359
CITED 3 FAVORITE 1 TOTAL DOWNLOAD COUNT 3520

3

1

3520

FİNANSAL RAPORLAMA STANDARTLARINA UYGUN HESAP PLANI TASLAĞI’NDAKİ HİZMET ÜRETİM MALİYETİ HESAPLARININ İNCELENMESİ VE TEKDÜZEN HESAP PLANI İLE KARŞILAŞTIRILMASI
Authors: Gürbüz Gökçen , Başak Ataman
Published: 2020 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.739402
CITED 2 FAVORITE 0 TOTAL DOWNLOAD COUNT 4099

2

0

4099

COMPARISON OF THE BASIC ISSUES BETWEEN KUMI FRS, BOBI FRS AND TAS/TFRS
Authors: Erkan Öztürk , Gürbüz Gökçen , Ömer Faruk Güleç
Published: 2019 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.616662
CITED 20 FAVORITE 1 TOTAL DOWNLOAD COUNT 6035

20

1

6035

İŞLETMELERDE HİLELERİN ÖNLENMESİNE YÖNELİK İÇ KONTROLLER VE BİST İMALAT SEKTÖRÜNDE BİR ARAŞTIRMA
Authors: Gürbüz Gökçen , Onur Tipi
Published: 2019 , Marmara University Journal of Economic and Administrative Sciences
DOI: 10.14780/muiibd.582316
CITED 7 FAVORITE 1 TOTAL DOWNLOAD COUNT 5764

7

1

5764

ADAPTATION of FINANCIAL STATEMENTS BASED on GENERAL COMMUNIQUE ON ACCOUNTING SYSTEM APPLICATION (GCASA) to FINANCIAL REPORTING STANDARD for LARGE and MEDIUM SIZED ENTERPRISES (FRS for LMEs) and A RATIO ANALYSIS
Authors: Hakan Cavlak , Başak Ataman , Gürbüz Gökçen
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.424763
CITED 5 FAVORITE 1 TOTAL DOWNLOAD COUNT 10095

5

1

10095

COMPARISON OF BOBİ FRS AND TFRS IN TERMS OF THE EFFECTS OF FINANCIAL REPORTS
Authors: Erkan Öztürk , Gürbüz Gökçen , Ömer Faruk Güleç
Published: 2018 , Research of Financial Economic and Social Studies
DOI: 10.29106/fesa.425384
CITED 18 FAVORITE 1 TOTAL DOWNLOAD COUNT 11019

18

1

11019

Analysis Of The Relationship Between Corporate Governance Perception And Corporate Governance Rating
Authors: Başak Ataman , Gürbüz Gökçen , Hakan Cavlak , Yasin Cebeci
Published: 2017 , Journal of Finance Letters
DOI: 10.33203/mfy.307179
CITED 3 FAVORITE 0 TOTAL DOWNLOAD COUNT 5917

3

0

5917

E-BOOK AND E-INVOICING PRACTICES FROM ACCOUNTING PRACTICES IN TURKEY
Authors: Gürbüz Gökçen , Mustafa Özdemir
Published: 2016 , Oneri
DOI: -
CITED 7 FAVORITE 1 TOTAL DOWNLOAD COUNT 11717

7

1

11717

A Research About Utilization Of Inventory Cost Formulas Under TMS 2 Inventory Standards In Food Sector
Authors: Gürbüz Gökçen , Yasin Cebeci
Published: 2016 , Journal of Finance Letters
DOI: 10.33203/mfy.312138
CITED 4 FAVORITE 0 TOTAL DOWNLOAD COUNT 9336

4

0

9336

A RESEARCH ON ACCOUNTING STANDARDS EDUCATION IN THE STATE UNIVERSITY GRADUATE PROGRAM IN TURKEY
Authors: Gürbüz Gökçen , Başak Ataman , Yasin Cebeci , Hakan Cavlak
Published: 2015 , Oneri
DOI: -
CITED 12 FAVORITE 0 TOTAL DOWNLOAD COUNT 2476

12

0

2476

Popular Publications: It is determined automatically by the researchers doing research in DergiPark according to the statistics of being added to the favorites. CrossRef Cited: The citations shown in DergiPark are drawn from CrossRef. For this, the cited and cited articles must be registered in CrossRef (DOI number). ^: Citation numbers are reflected in the system by DergiPark at certain periods.